西宁至成都铁路拉脊山越岭段主要工程地质问题及地质选线

The Main Engineering Geological Problems and Geological Route Selection of Ridge Section in Laji Mountain on Xining-Chengdu Railway

新建西宁至成都铁路拉脊山越岭段位于祁连地槽褶皱系东南部,地形地质条件复杂。详细分析拉脊山越岭段的主要工程地质问题,通过现场调查及深孔钻探等方法,鉴别中-新生代不同胶结、结构特征砂岩水稳性的差异,提出越岭段的地质选线原则:(1)隧道应尽量避开饱水弱胶结厚层状砂岩,尽量走行于泥岩中;(2)线路宜短距离、大角度且以简单工程类型通过活动断裂带;(3)线路应绕避巨型、大型滑坡及错落;(4)隧道应尽量避免走行于向斜核部等储水构造部位;(5)线路应避开小煤窑采空区范围。并研究比较中、东、西方案,得出东方案地质条件较优的结论。

The ridge section in Laji Mountain on the high speed railway from Xining to Chengdu is located in the southeastern part of the Qilian trough system with complex terrain and geological conditions.This paper analyzes the main engineering geological problems and identifies the differences in water stability of sandstone with different cementation and structural characteristics based on field investigation and deep-hole drilling. The principles of geologic route selection are proposed：（ 1） tunnels should avoid being located in thick sandstone saturated with water,and should be located in mudstone;（ 2） the route should pass through the active fault zone and the engineering should be short in distance,at large angle and constructed with simple form;（ 3） the route should keep away from giant and heavy landslides without being scattered;（ 4） tunnels should be away from ground water bearing areas;（ 5） zones of small coal miners should be avoided. Three schemes of Center,Easy and West are studied and the East scheme is proved better in geological conditions.